The trouble with all of this is that they can't just shut down the US internet. Yes, the internet was developed in conjunction with the British and several other countries, however, there is still a signifigant amount of hardlines and communications systems that are used to connect what is essentially "the internet" to the general public of the United States. Who owns these hardlines and sattilites? The United States.
An internet kill switch wouldn't be able to shut it down just like that with a virus or something, that just isn't feasible. What would more than likely happen is that when the order is given, all hardlines would be cut, essentially destroying communications with the sattilites. This would immediately cancel out the transmission of data from server to server, and shut down the internet. Would it only affect the US? The answer is a resounding FUCK NO.
Not every country can afford a communications web, so many countries piggyback off off the EU and US systems, thus avoiding the need to make their own. This is a problem, as the vast majority of these countries get that service from the United States, and if this kill switch were to be activated, the US and any other countries that use that comm system will be completely cut off from the rest of the world. Not only that, but a large portion of the internet's data is stored in US servers, which would devestate the internet if shut down. Even countries with their own comm systems would be affected, as many commerce and business sites are located on US servers, and a lot of foreigners and Europeans use US servers for their reliability and space.
Needless to say, that the very existance of this "kill switch" would be bordering on an international war crime. I can't even think about the abhorable disaster that could potentially take place if it were ever activated. Somebody seriously needs to step in and take charge of these incredibly unstable government officials.